A key election metric for Democrats is on a sign in your neighborhood

A month ago, I noticed an unsubtle correlation: In recent months, the extent to which Americans said the country was on the right track moved in concert with gas prices. In other words, as gas prices fell, American optimism rose. As prices rose, optimism fell.

This seems counterintuitive. We tend to assume that people are complicated, albeit rational, actors who process information and come to intricate conclusions about cause and effect. But that may be overcomplicating things. Looking at the same data for President Biden’s approval rating and for the Democratic position in generic-ballot polling (that is, polling that asks which party people plan to vote for in November) shows similar correlations.

One way we can visualize the relationship between two sets of data is to compare them directly on a chart. After all, if two numbers move in concert, they can be depicted literally moving in concert. One goes up, the other moves either up or down consistently. That sort of thing. So if we plot one set of numbers on the vertical axis of a chart (say, weekly gas price averages) and another on the horizontal axis (like FiveThirtyEight’s average of Biden’s approval polling), a correlation will be revealed as the two numbers are moving in concert.